Actually, the skiing season has already ended. There hasn't been much snow this year, and Spring is too warm so far, so most ski facilities are closed until next winter. That doesn't mean you can't ski, but your options are limited to the high altitude resorts like Zermatt and Saas Fee. Zermatt would be a good option: it's a car free town and easy to be reached by train. Please see the timetable for details. A Swiss Card or Swiss Transfer Ticket would cover your trip.

By the way, when going from Zermatt to Paris, there's no need to go back to Zurich, unless you have already booked. Traveling via Geneva or Basel would be quicker. The timetable will show you the best options.

Yes, you can travel from Interlaken, but these trips would take relatively long (check the timetable for details). I'm not sure whether that would still fit your desire not to rush. Since you mentioned you want to go to a ski resort: are you planning to go skiing? If so, I would really recommend to stay in a ski resort such as Zermatt, rather than making a day trip to Zermatt from Interlaken. It would take many hours before you finally reach the ski slopes.